Contact structures with intermediate frictional contact member



1965 F. KESSELRING ETA 3,214,559

CONTACT STRUCTURES WITH INTE FRICTIONAL CONTACT MEM Filed Aug. 14, 1963 2o 1 H0 I I4 I Zlk It J22 r 24 and Th INVENTORS ltz Kesselring eodor Mourer z zgm f M ATTORNEY WITNESSES f 5 W 9 United States Patent 3,214,559 CONTACT STRUCTURES WETH INTERMEDIATE FRICTIONAIL CONTACT MEMBER Fritz Kesselring, Kusnacht, Zurich, and Theodor Maurer,

Zurich, Switzerland, assignors to Siemens-Schuckertwerke Alrtiengesellschaft, Erlangen, Germany, a corporation of Germany Filed Aug. 14, 1963, Ser. No. 302,146 Claims priority, application Germany, Sept. 5, 1962, S 81,281 9 Claims. (Cl. 200-166) This invention relates generally to contact structures and, more particularly, to improved contact structures in which contact chattering, or bouncing is substantially reduced, or entirely eliminated.

It is a general object of the present invention to provide an improved separable contact structure particularly constructed to avoid contact chattering or bouncing.

Another object of the present invention is to provide an improved non-chattering separable contact structure for a fluid-blast type of circuit interrupter.

Still a further object of the present invention is the provision of an improved separable contact structure in which a frictional intermediate contact, having limited motion, is employed between the relatively stationary and movable contacts to prevent contact chattering or bouncing during the closing operation.

Preferably, the construction is additionally arranged to increase the contact pressure between the intermediate and movable contacts during the final portion of the closing travel of the movable contact.

As well known by those skilled in the art, the presence of chattering, or bouncing of the cooperable contacts during the final portion of the closing stroke has the concomitant deleterious effect of causing considerable erosion of the contact surfaces, so that after a few contact operations the contact surfaces being engaged are pitted, and the passage of current therethrough, because of the resistance, results in an undesired heating effect.

It is, accordingly, a further object of the present invention to provide an improved separable contact structure in which contact erosion and wear resulting from chattering, or bouncing of the contacts during the closing stroke is substantially avoided, or completely eliminated.

In United States patent application filed August 29, 1961, Serial No. 134,655, by Fritz Kesselring and Ernst Gisiger, entitled Synchronized Circuit Interrupter, and assigned to the assignee of the instant application, there 1 s illustrated and described a novel type of fluid-blast circu t interrupter in which the separable contact structure is arranged to be separated only during the descending portion of the alternating current wave. It is a further ob ect of the present invention to improve upon the contact structure set forth in the aforesaid application rendering the same suitable for the prevention of bouncing or chattering during the closing stroke and yet to take advantage of the synchronous method of operation.

Further objects and advantages will readily become ap parent upon reading the following specification, taken in conjunction with the drawing, in which:

FIGURE 1 is a diagrammatic vertical sectional view taken through an improved fluid-blast circuit interrupter embodying a contact structure of the type described herein;

FIG. 2 is a considerably enlarged vertical sectional view taken through the improved non-chattering contact structure of the instant application, with the contacts being illustrated in their fully closed position;

FIG. 3 is a view similar to FIG. 2 but illustrating the disposition of the contact structure at an intermediate point in the opening operation;

Patented Oct. 26, 1965 FIG. 4 is a view similar to FIG. 3 but illustrating the disposition of the several parts at a later point in the openlng operation; and,

FIG. 5 is a horizontal sectional view taken through the improved contact structure of FIG. 2 substantially along the line V-V of FIG. 2.

Referring to the drawing, and more particularly to FIG. 1 thereof, the reference numeral 1 generally designates a fluid-blast circuit interrupter. The fluid employed may be a suitable arc-extinguishing gas or liquid, but for purposes of illustration, there is shown, by way of example, a reservoir 2 containing a suitable arc-extinguishing gas 3, such as sulfurhexafluoride (SP gas under pressure.

Controlling the flow of the high-pressure sulfur-hexafluoride gas out of the high-pressure reservoir chamber 2 is a valve 4, which is preferably synchronized with the separation of the separable contact structure 5, as well known by those skilled in the art, to provide a blast of fluid out through the orifice structure 6 associated with a relatively stationary contact structure 7. FIG. 4 may be referred to in this connection as illustrating the direction of flow of the arc-extinguishing gas 3 in causing the interruption of an are 8, which is drawn between a movable rod-shaped contact 9 and the aforesaid relatively stationary contact structure 7.

In accordance with the principles of the present invention, the relatively stationary contact structure 7 comprises two component parts. As shown more clearly in FIGS. 2-4, the relatively stationary contact structure 7 comprises an apertured conducting relatively stationary contact plate 10 and an intermediate frictional member 11, which, when utilized in connection with a fluid-blast circuit interrupter of the type illustrated in FIG. 1, has an aperture 12 extending therethrough.

As shown, the frictional intermediate contact member 11 has a lower radially outwardly-extending flange portion 13 and an upper stop flange ring 14 suitably aflixed, as by screws 15, to the body portion 16 of the frictional intermediate contact 11. In addition, suitable means are provided for supplying friction between the intermediate frictional contact 11 and relatively stationary contact plate 10. Such means may assume the form of bearing surfaces 17, 18 of conical configuration between the conducting contact plate 10 and the conducting intermediate frictional contact 11.

Preferably, the relatively stationary contact plate 10 has a reamed portion 19 provided therein, within which the fiange portion 13 may extend, as shown more clearly in FIGS. 2-4 of the drawings. The stop-flange ring 14 serves the purpose of limiting the following travel of the frictional intermediate contact 11 with the lower movable contact 9 during the opening operation of the interrupter 1.

To assist the following travel of the frictional intermediate contact 11 with the lower movable rod-shaped contact 9 there is provided, by way of example, an aperturcd spring disk 20 secured to the contact plate 10 by means of a mounting ring 21 and a plurality of circumferentially-spaced bolts 22. The effect of the spring disk 29 is to bias the frictional intermediate contact 11 in a downward opening direction, so that the frictional member 11 follows the movable contact 9 as the latter descends in its opening travel. The frictional member 11, may assume the form of a split frictional ring, having a split portion 11a, so that during the closing operation, the frictional ring 11, which may be pre-stressed against the bearing surface 17 of the conducting plate 10 will have increased friction acting thereon during the final portion of the closing travel of the movable contact 9, namely from the position illustrated in FIG. 3 to the final closed-circuit position, as illustrated in FIG. 2 of the drawing. A line connection L may be secured to one of the bolts 22, and

another line connection L may be connected to a sliding contact 9a bearing against the side of the movable contact 9, as shown in FIG. 1.

During the opening operation, the arrangement is such that the movable contact 9 is moved downwardly by suitable means, not shown, together with a synchronization of the opening of the blast valve 4 so as to provide an accompanying blast of fluid 3, such as sulfur-hexafluoride gas out through the orifice opening 12. During the initial downward portion of the opening travel of the movable contact 9, the intermediate frictional split-ring member 11 follows therewith, until the stop flange 14 strikes the upper surface a of the contact plate 10, thereby halting any further downward opening travel of the intermediate frictional contact 11. Thereafter, the continued descending opening movement of the movable contact 9 causes a separation between the contacts 9, 11 to result in the establishment of an arc 8 drawn therebetween. This are 8 is subjected to a radial outward blasting of fiuid 3, as caused by synchronized opening of the blast valve 3 and as indicated by the arrows 24 of FIG. 4.

The construction is such that during the closing operation the engagement between the movable contact 9 and the frictional ring 11 causes an ever-increasing contact pressure therebetween and, in addition, provide increased frictional forces between the intermediate frictional member 11 and the surrounding apertured relatively stationary contact plate 10. The result is a nonchattering, non-bouncing closing operation to the ultimate closed position, as illustrated in FIG. 2 of the drawmg.

The contact construction 5 illustrated herein has been shown, by tests, to be particularly suitable for high-power circuit interrupters, and has resulted in non-chattering operation with current magnitudes of 100,000 amperes and more. By a suitable selection of the pre-stressing of the resilient intermediate contact member 11, and thereby of the frictional work encountered during the closing operation, it is possible to adapt the instant contact arrangement 5 to any given requirements.

A very important advantage of the present invention is the fact that together with the increased friction encountered during the final portion of the closing operation, there is, in addition, an increased contact pressure resulting between the movable contact 9 and the engaged frictional contact member 11.

Although there has been illustrated and described a specific structure, it is to be clearly understood that the same was merely for the purpose of illustration, and that changes and modifications may readily be made therein by those skilled in the art without departing from the spirit and scope of the invention.

We claim as our invention:

1. Separable contact structure including a relatively stationary contact and a cooperable movable contact movable relative thereto during the opening and closing operations, an intermediate frictional contact interposed between the relatively stationary and movable contacts and movable with the movable contact only for the final portion of the closing travel of the movable contact, said intermediate contact having a permanent electrical connection with said relatively stationary contact, and means providing friction between the intermediate frictional contact and the relatively stationary contact during such final portion of the closing travel of the movable contact.

2. Separable contact structure including a relatively stationary contact and a cooperable movable contact movable relative thereto during the opening and closing operations, an intermediate frictional contact interposed between the relatively stationary and movable contacts and movable with the movable contact only for the final portion of the closing travel of the movable contact,

said intermediate contact having a permanent electrical connection with said relatively stationary contact, means providing friction between the intermediate frictional contact and the relatively stationary contact during such final portion of the closing travel of the movable contact, and said means in addition supplying increased contact pressure between the intermediate frictional contact and the movable contact during such final portion of the closing travel of the movable contact.

3. In combination, a relatively stationary contact, an intermediate split ring-shaped contact and a movable contact, means defining conical bearing surfaces between the relatively stationary contact and said intermediate split ring-shaped contact, and means limiting the longitudinal travel of the intermediate split ring-shaped contact only to the final portion of the closing travel of the movable contact.

4. The combination of claim 3, wherein longitudinallydirected spring means acts to bias the split ring-shaped intermediate contact in the direction of the opening travel of the movable contact.

5. Separable contact structure for a fluid-blast circuit interrupter including a relatively stationary orifice-shaped contact and a cooperable movable contact movable relative thereto during the opening and closing operations, an intermediate orifice-shaped frictional contact interposed between the relatively stationary and movable contacts and movable with the movable contact only for the final portion of the closing travel of the movable contact, and means providing friction between the intermediate orificeshaped frictional contact and the relatively stationary contact during such final portion of the closing travel of the movable contact.

6. Separable contact structure for a fluid-blast circuit interrupter including a relatively stationary orifice-shaped contact and a cooperable movable contact movable relative thereto during the opening and closing operations, an intermediate orifice-shaped frictional contact interposed between the relatively stationary and movable contacts and movable with the movable contact only for the final portion of the closing travel of the movable contact, means providing friction between the intermediate orifice-shaped frictional contact and the relatively stationary contact during such final portion of the closing travel of the movable contact, and said means in addition supplying increased contact pressure between the intermediate frictional contact and the movable contact during such final portion of the closing travel of the movable contact.

7. In combination, a relatively stationary contact, an intermediate orifice-shaped split ring-shaped contact and a movable contact, means defining conical bearing surfaces between the relatively stationary contact and said References Cited by the Examiner UNITED STATES PATENTS 2/38 Kesselring 200148 7/48 Skeats 200-146 KATHLEEN H. CLAFFY, Primary Examiner.

BERNARD A. GILHEANY, Examiner. 

1. SEPARABLE CONTACT STRUCTURE INCLUDING A RELATIVELY STATIONARY CONTACT AND A COOPERABLE MOVABLE CONTACT MOVAVLE RELATIVE THERETO DURING THE OPENING AND CLOSING OPERATIONS, AN INTERMEDIATE FRICTIONAL CONTACT INTERPOSED BETWEEN THE RELATIVELY STATIONARY AND MOVABLE CONTACTS AND MOVABLE WITH THE MOVABLE CONTACT ONLY FOR THE FINAL PORTION OF THE CLOSING TRAVEL OF THE MOVABLE CONTACT, SAID INTERMEDIATE CONTACT HAVING A PERMANENT ELECTRICAL CONNECTION WITH SAID RELATIVELY STATIONARY CONTACT, AND MEANS PROVIDING FRICTION BETWEEN THE INTERMEDIATE FRICTIONAL CONTACT AND THE RELATIVELY STATIONARY CONTACT DURING SUCH FINAL PORTION OF THE CLOSING TRAVEL OF THE MOVABLE CONTACT. 